The present invention relates to vehicles, particularly vehicles for use by the mobility impaired. The invention finds particular application in conjunction with manually or arm powered wheelchairs and will be described with particular reference thereto. However, it is to be appreciated that the present invention may also find application with other wheelchairs and vehicles, such as patient transports, strollers, carts, and the like.
Heretofore, wheelchairs have commonly included wheel locks for locking the large, rear wheels against rotation. A wheel lock assembly was commonly mounted to the frame of the wheelchair adjacent each rear wheel. Each wheel lock assembly included a hand operated lever which was connected by a mechanical linkage to a member for engaging the tread at the periphery of the rear wheel. When the lever was disposed in a free wheeling position, the member was spaced away from the wheel and the tire allowing the wheel to rotate freely. When the handle was moved to a locked position, the member was moved into the tire with sufficient force that it was pressed into and temporarily deformed the outer surface of the tire.
One of the problems with the prior art rear wheel lock was that they required either a relatively large manual effort or a long throw to lock the wheels against rotation. Another problem was that they were unable to provide unidirectional locking of the wheels.
If the operator were to stop propelling the wheelchair up a hill and relax, gravity would urge the chair to roll backwards. Similarly, when the operator removed his hands from the wheels to push a door, the pushing tended to move the wheelchair rearwardly. Note that if a door with an automatic closure spring had sufficient resistance to movement, the operator might have to lock the wheels against rotation to push the door partially open. However, while the operator was releasing the manual brakes, the door would tend to close. To enable the operator to limit movement of the wheels to the forward direction only, hill holder mechanisms are commonly available on wheelchairs.
It has been proposed to add hill holder mechanisms or one way clutches to the hub of the rear wheels. However, these one way clutches were relatively expensive and mechanically complex. Other hill holders have been devised which interact with the tire at the periphery of the wheels. However, such peripheral acting hill holders are separate and independent structures from the wheel lock. Although the separate wheel lock/hill holder provided greater flexibility, it was more mechanically cumbersome, hence, more expensive. Further, it necessitated mounting a second structure on the wheelchair frame contiguous with the wheel periphery.
The present invention provides a combined hill holder and wheel lock assembly which overcomes the above referenced problems and others.